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1.
The crystal structure of poly(ω‐pentadecalactone) (PPDL) synthesized by enzyme‐catalyzed polymerization was determined by full‐profile refinement. A pseudo‐orthorombic monoclinic unit cell with dimensions a = 7.49(1), b = 5.034(9), and c = 20.00(4)Å (fiber axis), and α = 90.06(4)° hosts two monomeric units belonging to polymer chains with opposite orientation, according to the P21 space‐group symmetry. A close similarity to the crystal structure of poly(?‐caprolactone) was evident. However, the even number of backbone atoms in the monomer unit of PPDL leads to a lower crystal symmetry. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 1009–1013, 2003  相似文献   

2.
X‐ray structure analysis was carried out in order to clarify the crystal structure and structural disorder of poly‐(p‐phenylenebenzobisthiazole). Two molecular chains pass through an oblique unit cell with parameters a = 11.60 Å, b = 3.588 Å, γ = 92.0° and the plane group p2. The angle between the phenylene and benzobisthiazole rings was estimated as 20.5°. Poly‐(p‐phenylenebenzobisthiazole) includes the disorder with respect to the molecular height, because the first and third layer lines are diffuse streak. On the ac plane, the molecular heights are disordered by 1/2 because 102, 602, and 404 reflections can be observed. On the bc plane, the molecular heights are disordered by every 1/5 because the 015 reflection can be observed. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 376–382, 2000  相似文献   

3.
The effect of the uniaxial and biaxial stretching and subsequent solution annealing of extrusion‐cast polyamide‐11 films on the crystalline structure and morphology was investigated with differential scanning calorimetry, wide‐angle X‐ray diffraction (WAXD), Fourier transform infrared spectroscopy, and small‐angle X‐ray scattering (SAXS). The extrusion‐cast polyamide‐11 films exhibited elevations in the glass‐transition and cold‐crystallization temperatures with a constant crystallinity and a constant melting point during aging under room conditions (20–26 °C and 20–31% relative humidity). WAXD and SAXS suggested that chain‐folded lamellae of coexisting α‐ and β‐crystals existed in all the stretched polyamide‐11 films. WAXD pole figures indicated that hydrogen bonds in the hydrogen‐bonded sheets of these two crystalline forms apparently formed between antiparallel chain molecules. The unit cell parameters [a = 9.52 Å, b = 5.35 Å, c = 14.90 Å (chain axis), α = 48.5°, β = 90°, and γ = 74.7° for a triclinic α form and a = 9.52 Å, b = 14.90 Å (chain axis), c = 4.00 Å, α = 90°, β = 67.5°, and γ = 90° for a monoclinic β form] for polyamide‐11 crystals were proposed according to the results of this study and the results of previous investigators. The unit cell parameters of the stretched extrusion‐cast polyamide‐11 films varied, depending on the stretching conditions (the stretch temperature and stretch ratio). As the stretch temperature and stretch ratio were increased, the crystal became more similar to the form described previously and was accompanied by an increase in the long spacing of crystalline lamellae. Annealing the stretched films in a boiling 20% formic acid solution made slightly more perfected crystals. The hydrogen‐bonding α(010) + β(002) planes, which are nearly parallel to both amide group planes and zigzag methylene sequence planes of the biaxially stretched films were found to be parallel to the film surface. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 2624–2640, 2002  相似文献   

4.
Poly(octamethylene terephthalate) (POT), a semicrystalline aromatic polyester, is synthesized by melt‐condensation reaction, and its thermal property and crystal structure are investigated by using differential scanning calorimetry, X‐ray diffraction, and molecular modeling methods, respectively. It is revealed that the synthesized POT sample has comparably low melting temperature of 131 °C and forms one crystalline phase. Based on two‐dimensional X‐ray fiber diagram and molecular modeling analyses, the crystal structure of POT is identified to be triclinic with dimensions of a = 4.560 Å, b = 5.597 Å, c = 18.703 Å, α = 104.87°, β = 119.45°, and γ = 100.32°, in which one chemical repeating unit of POT with all‐trans conformation of octamethylene group is packed according to the space group of . © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 276–283, 2009  相似文献   

5.
Single crystals of poly(naphthalic anhydride) (PNA) have been grown using our confined thin film melt polymerization technique. Lamellae, 70–100 Å thick, are found for the crystals polymerized at 180°C with thinner lamellae for a 200°C polymerization temperature. In addition, irregular lath-shaped crystals are found for both polymerization temperatures, apparently formed by a solid-state polymerization process within the original needle-like monomer crystals. The crystal structure of PNA has been studied by electron diffraction (ED) and computer modeling based on seven different zonal ED patterns. It is found that, in most cases, two or three different zonal patterns are superimposed with a common plane, suggesting variable chain tilting even in individual lamellae. Shearing of the material shortly after the initiation of polymerization, permitted obtaining an additional [010] zone ED pattern. A monoclinic unit cell with one chain, two repeat units is proposed based on measurements of 21 independent reflections; the space group is Pc11; a = 6.26 Å, b = 4.33 Å, c = 18.60 Å, and α = 122.5°. The computer-simulated (Cerius2) molecular conformation and chain packing are described with the corresponding simulated electron diffraction patterns being in good agreement with the observed ones. © 1997 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 35 : 1575–1588, 1997  相似文献   

6.
Structure and Magnetic Properties of Bis{3‐amino‐1,2,4‐triazolium(1+)}pentafluoromanganate(III): (3‐atriazH)2[MnF5] The crystal structure of (3‐atriazH)2[MnF5], space group P1, Z = 4, a = 8.007(1) Å, b = 11.390(1) Å, c = 12.788(1) Å, α = 85.19(1)°, β = 71.81(1)°, γ = 73.87(1)°, R = 0.034, is built by octahedral trans‐chain anions [MnF5]2– separated by the mono‐protonated organic amine cations. The [MnF6] octahedra are strongly elongated along the chain axis (<Mn–Fax> 2.135 Å, <Mn–Feq> 1.842 Å), mainly due to the Jahn‐Teller effect, the chains are kinked with an average bridge angle Mn–F–Mn = 139.3°. Below 66 K the compound shows 1D‐antiferromagnetism with an exchange energy of J/k = –10.8 K. 3D ordering is observed at TN = 9.0 K. In spite of the large inter‐chain separation of 8.2 Å a remarkable inter‐chain interaction with |J′/J| = 1.3 · 10–5 is observed, mediated probably by H‐bonds. That as well as the less favourable D/J ratio of 0.25 excludes the existence of a Haldene phase possible for Mn3+ (S = 2).  相似文献   

7.
The living synthesis of poly(1,3‐cyclohexadiene) was performed with an initiator adduct that was synthesized from a 1:2 (mol/mol) mixture of N,N,N,N′‐tetramethylethylenediamine (TMEDA) and n‐butyllithium. This initiator, which was preformed at 65 °C, facilitated the synthesis of high‐molecular‐weight poly(1,3‐cyclohexadiene) (number‐average molecular weight = 50,000 g/mol) with a narrow molecular weight distribution (weight‐average molecular weight/number‐average molecular weight = 1.12). A plot of the kinetic chain length versus the time indicated that termination was minimized and chain transfer to the monomer was eliminated when a preformed initiator adduct was used. Chain transfer was determined to occur when the initiator was generated in situ. The polymerization was highly sensitive to both the temperature and the choice of tertiary diamine. The use of the bulky tertiary diamines sparteine and dipiperidinoethane resulted in poor polymerization control and reduced polymerization rates (7.0 × 10−5 s−1) in comparison with TMEDA‐mediated polymerizations (1.5 × 10−4 s−1). A series of poly(1,3‐cyclohexadiene‐block‐isoprene) diblock copolymers were synthesized to determine the molar crossover efficiency of the polymerization. Polymerizations performed at 25 °C exhibited improved molar crossover efficiencies (93%) versus polymerizations performed at 40 °C (80%). The improved crossover efficiency was attributed to the reduction of termination events at reduced polymerization temperatures. The microstructure of these polymers was determined with 1H NMR spectroscopy, and the relationship between the molecular weight and glass‐transition temperature at an infinite molecular weight was determined for polymers containing 70% 1,2‐addition (150 °C) and 80% 1,4‐addition (138 °C). © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 1216–1227, 2005  相似文献   

8.
The blue copper complex compounds [Cu(phen)2(C6H8O4)] · 4.5 H2O ( 1 ) and [(Cu2(phen)2Cl2)(C6H8O4)] · 4 H2O ( 2 ) were synthesized from CuCl2, 1,10‐phenanthroline (phen) and adipic acid in CH3OH/H2O solutions. [Cu(phen)2‐ (C6H8O4)] complexes and hydrogen bonded H2O molecules form the crystal structure of ( 1 ) (P1 (no. 2), a = 10.086(2) Å, b = 11.470(2) Å, c = 16.523(3) Å, α = 99.80(1)°, β = 115.13(1)°, γ = 115.13(1)°, V = 1617.5(5) Å3, Z = 2). The Cu atoms are square‐pyramidally coordinated by four N atoms of the phen ligands and one O atom of the adipate anion (d(Cu–O) = 1.989 Å, d(Cu–N) = 2.032–2.040 Å, axial d(Cu–N) = 2.235 Å). π‐π stacking interactions between phen ligands are responsible for the formation of supramolecular assemblies of [Cu(phen)2(C6H8O4)] complex molecules into 1 D chains along [111]. The crystal structure of ( 2 ) shows polymeric [(Cu2(phen)2Cl2)(C6H8O4)2/2] chains (P1 (no. 2), a = 7.013(1) Å, b = 10.376(1) Å, c = 11.372(3) Å, α = 73.64(1)°, β = 78.15(2)°, γ = 81.44(1)°, V = 773.5(2) Å3, Z = 1). The Cu atoms are fivefold coordinated by two Cl atoms, two N atoms of phen ligands and one O atom of the adipate anion, forming [CuCl2N2O] square pyramids with an axial Cl atom (d(Cu–O) = 1.958 Å, d(Cu–N) = 2.017–2.033 Å, d(Cu–Cl) = 2.281 Å; axial d(Cu–Cl) = 2.724 Å). Two square pyramids are condensed via the common Cl–Cl edge to centrosymmetric [Cu2Cl2N4O2] dimers, which are connected via the adipate anions to form the [(Cu2(phen)2Cl2)(C6H8O4)2/2] chains. The supramolecular 3 D network results from π‐π stacking interactions between the chains. H2O molecules are located in tunnels.  相似文献   

9.
2‐Nitroimino‐5‐nitro‐hexahydro‐1,3,5‐triazine (NNHT), was synthesized and its structure was determined by single‐crystal X‐ray diffraction. The crystal is monoclinic, space group P21/c with crystal parameters of a = 9.4031(13) Å, b = 8.5891(12) Å, c = 9.0200(13) Å, β = 91.213(2)°, V = 728.33(18) Å3, Z = 4, F(000) = 392, Dc = 1.734 g/cm3. The experimental geometry of NNHT was input to Gaussian‐03W program and optimized using DFT‐B3LYP/6‐311++G** method. The IR frequencies and NMR chemical shift were carried out and compared well with those of the experimental. The atomic net charges and the population analysis are discussed. The heat of formation (HOF) for NNHT was evaluated by designing an isodesmic reaction. The detonation velocity (D) and detonation pressure (P) were estimated by using the well known Kamlet‐Jacobs equation, based on the theoretical HOF.  相似文献   

10.
Three ternary rare earth [NdIII ( 1 ), SmIII ( 2 ) and YIII ( 3 )] complexes based on 3‐[(4,6‐dimethyl‐2‐pyrimidinyl)thio]‐propanoic acid (HL) and 1,10‐phenanthroline (Phen) were synthesized and characterized by IR and UV/Vis spectroscopy, TGA, and single‐crystal X‐ray diffraction. The crystal structures showed that complexes 1 – 3 contain dinuclear rare earth units bridged by four propionate groups and are of general formula [REL3(Phen)]2 · nH2O (for 1 and 2 : n = 2; for 3 : n = 0). All rare earth ions are nine‐coordinate with distorted mono‐capped square antiprismatic coordination polyhedra. Complex 1 crystallizes in the monoclinic system, space group P21/c with a = 16.241(7) Å, b = 16.095(7) Å, c = 19.169(6) Å, β = 121.48(2)°. Complex 2 crystallizes in the monoclinic system, space group P21/c with a = 16.187(5) Å, b = 16.045(4) Å, c = 19.001(4) Å, β = 120.956(18)°. Complex 3 crystallizes in the triclinic system, space group P1 with a = 11.390(6) Å, b = 13.636(6) Å, c = 15.958(7) Å, α = 72.310(17)°, β = 77.548(15)°, γ = 78.288(16)°. The antioxidant activity test shows that all complexes own higher antioxidant activity than free ligands.  相似文献   

11.
The crystal structure of poly(m-phenyulene isophthalamide) was determined by x-ray analysis. The triclinic cell, with a = 5.27 Å, b = 5.25 Å, c (fiber axis) = 11.3 Å, α = 111.5°, β = 111.4° and γ = 88.0° and space group P1, contains one monomeric unit. The crystal density is 1.47 g/cc. The molecules in the crystal are contracted by 1 Å per monomeric unit from the fully extended conformation, and the planes of the benzene rings and adjacent amide groups make angles of about 30°. The crystal is composed of molecular chains connected by N? H···O hydrogen bonds along the a and b axes forming a “jungle gym” network structure. The low tensile modulus of this polymer as compared with that of poly(p-phenylene terephthalamide) is attributed to the contracted molecular conformation.  相似文献   

12.
A series of crystals of phenyl‐capped tetraaniline in the leucoemeraldine oxidation state were obtained at different isothermal temperatures and were observed directly under transmission electron microscope. The crystals obtained at higher temperatures exhibit more perfect structures than those obtained at lower temperatures. Both the lamella thickness and the crystal size increase with crystallization temperature. The tetraaniline is apt to form larger scale crystals under lower degree of supercooling. However, their crystal structures keep steady with the crystallization temperature. The tetramer was found to adopt a monoclinic lattice with unit cell parameter of a = 13.93 Å, b = 8.82 Å, c = 23.20 Å, and β = 95.03°, as determined using electron diffraction tilting method combined with wide‐angle X‐ray diffraction experiment. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 764–769, 2006  相似文献   

13.
A new crystal modification was found in poly(ethylene oxide) stretched about two-fold after necking at room temperature. An x-ray diffraction analysis indicated that the planar zigzag molecule passes through a triclinic unit cell with parameters α = 4.71 Å, b = 4.44 Å, c (fiber axis) = 7.12 Å, α = 62.8°, β = 93.2°, and γ = 111.4°. The space group is P1 ?Ci1. Packing of the molecule is very similar to that of monoclinic polyethylene.  相似文献   

14.
The crystal structures of the M2NaIO6 series (M = Ca, Sr, Ba), prepared at 650 °C by ceramic methods, were determined from conventional laboratory X‐ray powder diffraction data. Synthesis and crystal growth were made by oxidizing I with O2(air) to I7+ followed by crystal growth in the presence of NaF as mineralizator, or by the reaction of the alkali‐metal periodate with the alkaline‐earth metal hydroxide. All three compounds are insoluble and stable in water. The barium compound crystallizes in the cubic space group Fm3m (no. 225) with lattice parameters of a = 8.3384(1) Å, whereas the strontium and calcium compounds crystallize in the monoclinic space group P21/c (no. 14) with a = 5.7600(1) Å, b = 5.7759(1) Å, c = 9.9742(1) Å, β = 125.362(1)° and a = 5.5376(1) Å, b = 5.7911(1) Å, c = 9.6055(1) Å, β = 124.300(1)°, respectively. The crystal structure consists of either symmetric (for Ba) or distorted (for Sr and Ca) perovskite superstructures. Ba2NaIO6 contains the first perfectly octahedral [IO6]5– unit reported. The compounds of the ortho‐periodates are stable up to 800 °C. Spectroscopic measurements as well as DFT calculations show a reasonable agreement between calculated and observed IR‐ and Raman‐active vibrations.  相似文献   

15.
The crystallization kinetics of biodegradable poly(butylene succinate‐co‐adipate) (PBS/A) copolyester was investigated by using differential scanning calorimetry (DSC) and polarized optical microscopy (POM), respectively. The Avrami and Ozawa equations were used to analyze the isothermal and nonisothermal crystallization kinetics, respectively. By using wide‐angle X‐ray diffraction (WAXD), PBS/A was identified to have the same crystal structure with that of PBS. The spherulitic growth rates of PBS/A measured in isothermal conditions are very well comparable with those measured by nonisothermal procedures (cooling rates ranged from 0.5 to 15 °C/min). The kinetic data were examined with the Hoffman–Lauritzen nucleation theory. The observed spherulites of PBS/A with different shapes and textures strongly depend on the crystallization temperatures. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 3231–3241, 2005  相似文献   

16.
Two new trans‐disubstituted cyclam ligands; 1,8‐di(6‐hydroxymethylpyridin‐2‐ylmethyl)‐1,4,8,11‐tetra‐azacyclotetradecane ( 5 ) and 1,8‐dimethyl‐4, 11‐di(6‐hydroxymethylpyridin‐2‐ylmethyl)‐1,4,8,11 ‐tetraaza‐cyclotetradecane ( 6 ); have been synthesized and characterized. The crystal structures of ligand 6 and its Ni(II) and Co(II) complexes have been determined. Crystal data are given for 6 , space group, P21/c, a = 11.095 (6) Å, b = 9.467 (5) Å, c = 13.283 (8) Å; β = 106.95 (5)°, Z = 2, R = 0.0715; for [Ni 6 ](C104)2, space group P21/c, a = 9.4848 (14) Å, b = 33.941(6) Å, c = 9.793(2) A, β = 95.264(14)°, Z = 4, R = 0.0567; for [Co 6 ](C104)2, space group, P21/c, a = 9.440 (6) Å, b = 33.848 (13) Å, c = 9.820 (3) Å, β = 95.16(3)°, Z = 4, R = 0.0718. In both complexes, the metal atoms are six‐coordinate with only one of the pendants interacting with the central metal atom and the other pendant remaining uncoordinated.  相似文献   

17.
Two new cobalt complexes were successfully synthesized from the reaction of binaphthyl Schiff base 2 with Co(OAc)2 in the presence of sodium methoxide at 80 °C for 24 h and Co(acac)3 in toluene under reflux. Their unique crystal structures are unambiguously disclosed by X‐ray analysis. Complex 3 is triclinic, space group P1 , unit cell dimensions a = 10.742(2) Å, b = 11.153(2) Å, c = 12.715 Å, α = 79.865(3) °, β = 76.053 °, γ = 72.532(4) °, volume 1401.3(5) Å3, Z = 2. Complex 4 is triclinic, space group P1 , unit cell dimensions a = 10.801(2) Å, b = 12.554(3) Å, c = 15.219(3) Å, α = 105.672(4) °, β = 103.048 °, γ = 104.594(4) °, volume 1824.8(7) Å3, Z = 2, calculated density 1.428 Mg m−3. Copyright © 2003 John Wiley & Sons, Ltd.  相似文献   

18.
The new quaternary thiogermanates, ATaGeS5 (A = K, Rb, Cs) were prepared with the use of halide fluxes and the crystal structures of the compounds were determined by single‐crystal X‐ray diffraction methods. The compounds are isostructural and crystallize in space group P\bar{1} of the triclinic system with two formula units in a cell of dimensions: a = 6.937(1) Å, b = 6.950(2) Å, c = 8.844(3) Å, α = 71.07(2)°, β = 78.56(2)°, γ = 75.75(2)°, V = 387.6(2) Å3 for KTaGeS5; a = 6.996(3) Å, b = 7.033(3) Å, c = 8.985(4) Å, α = 70.33(3)°, β = 78.12(4)°, γ = 75.63(4)°, V = 399.6(3) Å3 for RbTaGeS5; a = 7.012(4) Å, b = 7.202(3) Å, c = 9.267(5) Å, α = 68.55(3)°, β = 77.27(4)°, γ = 74.75(4)°, V = 416.2(4) Å3 for CsTaGeS5. The structures of ATaGeS5 (A = K, Rb, Cs) are comprised of anionic infinite two‐dimensional {}_\infty^2 [TaGeS5] layers separated from one another by alkali metal cations (A+). Each layer is made up of tantalum centered sulfur octahedra and pairs of edge‐sharing germanium centered sulfur tetrahedra. The classical charge valence of these compounds should be represented by [A+][(Ta5+)(Ge4+)(S2–)5]. UV/Vis diffuse reflectance measurements indicate that they are semiconductors with optical bandgaps of ca. 2.0 eV.  相似文献   

19.
X-ray diffraction patterns were obtained for as-cast and oriented films of poly(γ-benzyl L -glutamate) and a comparison was made of the molecular packing of the α-helices in forms B and C. Form B snowed Bragg reflections on the layer lines as well as on the equator. The spacings were explained by a monoclinic unit cell comprising two chains, with a = 29.06 Å, b = 13 20 Å, c = 27.27 Å α = γ = 90°. and β = 96°. The chains contained in this unit cell and consequently alternating in the crystal have opposite chain directions. Form C showed continuous scattering on the layer lines and reflections on the equator. This form, therefore, is a nematiclike paracrystal in which the packing of α-helices is periodic in the direction lateral to the chain axis (a = 14.8–115.2 Å, b = 14.3–14.8 Å, c = 27 Å, and γ = 118°–120°), but the relative levels of the chains along the chain axes are displaced. The formation of form C may be attributed to random placement of two chains with mutually opposite chain directions.  相似文献   

20.
The crystal structure of 1,4-benzenedithiol (BDT) was determined by the Rietveld method based on the calculation of the atomic coordinates of the BDT molecule using the Molecular Mechanics Program (MMP2). The refined crystal structure of BDT was monoclinic P21/c with dimensions, a = 7.795, b = 7.290, c = 5.955 Å, β = 92.16°, z = 2. The R factor of the refined structure was 0.038. Using above results, the mechanism of solid-state addition polymerization of BDT to 1,4-diethynylbenzene (DEB) was studied. Sublimed BDT piles up onto glass plate substrate and forms the layer structure along with the a axis. An inclination angle of the piled BDT column was 60° toward the substrate surface. DEB crystal structure was also monoclinic P21/c with a = 4.007, b = 6.018; c = 15.340 Å, β = 91.42°, z = 2. Sublimation of equimolar mixture of BDT and DEB gave a crystal having 1 : 1 composition, in which DEB column is situated between the columns of BDT. Relative arrangement of both monomers was suitable for the addition of  SH and  CCH groups, since the distance between the two groups is 3.3 Å by CERIUS II calculation. Therefore, the addition polymerization of BDT to DEB easily proceeded by UV irradiation and the resulting polymer had a highly layer structure along with the a axis of BDT crystal. Tentatively estimated crystal structure of polymer obtained is monoclinic with a = 7.73, b = 7.30, c = 5.95 Å, β = 92.16°. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35 : 1621–1625, 1997  相似文献   

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